Victoria will stay in lockdown beyond the original five days after recording 13 more locally acquired cases and exposure sites popping up across the state.

Premier Daniel Andrews says he plans to announce the length of the extension on Tuesday morning.

There are almost 300 Canberrans under stay-at-home rules after returning to the capital from Victoria.

ACT Health imposed the orders for anyone entering from Victoria after 11.59pm Thursday, as the state's lockdown began.

ACT authorities will likely announce an extension to those orders tomorrow after the new lockdown timeline is confirmed.

These rules are imposed when a state goes into lockdown to mirror those requirements.

More than 500 people are also under stay-at-home rules due to the NSW COVID-19 outbreak.

Almost 450 people are in quarantine in Canberra after visiting COVID-19 affected areas.

Canberra went another day without a new Covid case while almost 700 negative tests were returned.

There were 13 new local infections in Victoria in the 24 hours to Monday morning, one of which was a case in Mildura, previously announced by authorities.

Mr Andrews said there were too many chains of transmission for the lockdown to lift at the original time of midnight Tuesday.

"We are running alongside this virus, but we're not yet in front of it," he said.

"We've gone hard and early and I think we have avoided, in fact I know we have avoided something altogether worse."

Mr Andrews said testing figures, exposure sites and test results on Monday would guide decision on any extension to the current restrictions.

READ MORE:

All the new coronavirus cases are linked to the current outbreaks of the Delta variant in the state, which originated in NSW.

Among the new cases is a household contact of the Mildura case revealed on Sunday, two are Trinity Grammar students, another is a close contact of a Phillip Island case, one is a case linked to AAMI Park and another was at the Euro 2020 viewing at Crafty Squire pub in the Melbourne CBD.

"That final case that Crafty Squire is of concern," Chief Health Officer Brett Sutton said.

" It is absolutely an example of how quickly this variant is moving in the short time we are seeing between exposure and then being infectious and onward transmission.

"So while we acted as conservatively as possible in declaring Crafty Squire a high-risk venue, we didn't necessarily expect there to be transmission there.

"The fact it has occurred some 30 hours after being exposed is absolutely a feature of the Delta variant."

With more cases appearing connected to the Melbourne Cricket Ground and AAMI Park cases, contact definitions have been expanded and authorities are asking for more people to go and get tested.

Our journalists work hard to provide local, up-to-date news to the community. This is how you can continue to access our trusted content: